Method and system for tire/whell disturbance compensation

ABSTRACT

The invention is directed to a method for introducing a compensating material into a tire/wheel assembly by providing at least one self-contained batch of a compensating material having a predetermined amount of such material and being selectively transferable into a tire. The at least one batch of material remains substantially self-contained for shipping and handling. The at least one batch is then transferred into the tire, and the tire is thereafter mounted onto a vehicle for operation or otherwise rotated wherein the at least one self-contained batch of material disperses the material within the tire upon rotation.

TECHNICAL FIELD

[0001] This invention relates to a method and system for introducing apredetermined amount of a force compensating material into a wheel/tireassembly for counteracting radial and lateral force variations at thetire/road footprint of a pneumatic tire.

BACKGROUND OF THE INVENTION

[0002] A typical motor vehicle is generally characterized as comprisingan unsprung mass and a sprung mass. The unsprung mass generally consistsof all of the parts of the vehicle not supported by the vehiclesuspension system such as the tire/wheel assembly, steering knuckles,brakes and axles. The sprung mass, conversely is all of the parts of thevehicle supported by the vehicle suspension system. The unsprung masscan be susceptible to disturbances and vibration from a variety ofsources such as worn joints, misalignment of the wheel, brake drag,irregular tire wear, etc. Because vehicular tires support the sprungmass of a vehicle on a road surface and such tires are resilient, anyirregularities in the uniformity or dimensions of the tire, anydimensional irregularities in the wheel rim, and/or any dynamicimbalance or misalignment of the tire/wheel assembly will causedisturbances and vibrations to be transmitted to the sprung mass of thevehicle thereby producing an undesirable or rough vehicle ride, as wellas reducing handling and stability characteristics of the vehicle.Severe vibration can result in dangerous conditions such as wheel trampor hop and wheel shimmy (shaking side-to-side).

[0003] It is now standard practice to reduce some of these adversevibrational effects by balancing the wheel rim and tire assembly byusing a balance machine and clip-on lead weights. The lead balanceweights are placed on the rim flange of the wheel and clamped in placein a proper position as directed by the balancing machine. The balancingprocedure can reduce imbalance in the tire/wheel assembly, however,perfect balance is rarely achieved. Balancing is not an exact art andthe results are dependent upon the specific set up of a tire/wheelassembly on a specific balancer at that moment in time. Balancing is animprovement and will reduce the vibration of the tire/wheel assembly incomparison to an unbalanced tire/wheel assembly. However, even perfectbalancing of the tire/wheel assembly does not necessarily mean that thetire will roll smoothly. The balancing of the tire/wheel assembly mustnecessarily be done in an unloaded condition. When the balanced tire isplaced on the vehicle, the weight of the vehicle acts on the tirethrough the interface or contact area of the tire and the road surfacewhich is commonly known as the tire footprint. Irregularities in thetire are common such that even a perfectly balanced tire can have severevibrations due to non-uniformities in the tire which result in unequalforces within the tire footprint.

[0004] A level of non-uniformity is inherent in all tires. In the art ofmanufacturing pneumatic tires, rubber flow in the mold or minordifferences in the dimensions of the belts, beads, liners, treads, pliesof rubberized cords or the like, sometimes cause non-uniformities in thefinal tire. When non-uniformities are of sufficient magnitude, they willcause force variations on a surface, such as a road, against which thetires roll and thereby produce vibrational and acoustical disturbancesin the vehicle upon which the tires are mounted. Regardless of the causeof the force variations, when such variations exceed the acceptableminimum level, the ride of a vehicle utilizing such tires will beadversely affected.

[0005] Balancing of the tires has also been accomplished by usingmethods other than balance machines and lead weights. For example, Fogalin U.S. Pat. No. 5,073,217 disclosed a method of balancing a vehicletire/wheel assembly by introducing a pulverulent synthetic plasticmaterial into the interior chamber of the tire wheel assembly. Thepulverulent synthetic plastic material has the added effect ofcompensating for the radial and lateral force variations generated atthe tire road interface. The movement of the pulverulent syntheticplastic material within the tire is proportional to the downward forceof the vehicle weight and the centrifugal force due to the tirerotation. Also, it has been found for some tire/wheel assemblies,particularly for use with passenger vehicles, a combination of leadweight balancing or the like with the addition of a predetermined amountof material introduced into the tire/wheel assembly to compensate forradial and lateral force variations at the tire/road footprint of apneumatic tire of a vehicle. Such disturbances are due to tire/wheelassembly imbalance, non-uniformity of the tire, temporary disturbancesin the road surface, or other vibrational effects of the unsprung massof a vehicle.

[0006] While the use of a compensating material introduced into theinterior of the tire has been found to work effectively, either alone orin combination with other balancing techniques, a limitation has beenfound in how to introduce this material into the tire. In the priorapproaches, the material is suspended in an air stream and introducedinto a tire through a hose line and valve stem used for inflation of atire. Although such an approach works sufficiently, this method ofdelivery of a compensating material is in some instances an inconvenientdelivery method, and may result in contamination of a work place where awheel assembly is being balanced. This delivery system has further beenutilized in the aftermarket environment to facilitate balancing ofreplacement tires, and no effective approach to introducing suchmaterial into a tire/wheel assembly at original manufacture has beenprovided.

[0007] There is therefore a need for an improved method and system fordelivery of a compensating material into the interior of a tire, in asimple and effective manner.

SUMMARY OF THE INVENTION

[0008] It is therefore an object of the present invention to provide amethod for introducing a compensating material into the interior of atire to provide compensation for radial and lateral force variations atthe tire/road footprint.

[0009] These and other aspects and objects of the invention are providedby a method for introducing a compensating material into a tire/wheelassembly comprising the steps of providing at least one self-containedbatch of a compensating material, providing a tire, transferring said atleast one self-contained batch of compensating material into an interiorof said tire, and mounding said tire on a wheel to form a tire/wheelassembly.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] This invention will now be described in further detail withreference to the accompanying drawings, in which:

[0011]FIG. 1 is a fragmentary side elevational view of a conventionalwheel assembly including a tire carried by a rim, and illustrates alower portion or “footprint” of the tire tread resting upon and bearingagainst an associated supporting surface, such as a road.

[0012]FIG. 2 is an axial vertical cross sectional view through the wheelassembly of FIG. 1 and additionally illustrates the lateral extent ofthe footprint when the tire rests under load upon the road surface.

[0013]FIG. 3 is an enlarged cross sectional view identical to FIG. 2,and illustrates the manner in which synthetic polymeric resinpulverulent material is deposited with an interior of a tire through anassociated tire valve.

[0014]FIG. 4 is a cross sectional view of the wheel assembly of FIG. 3during rotation, and illustrates a plurality of radial load forces ofdifferent variations or magnitudes reacting between the tire and theroad surface as the tire rotates, and the manner in which the polymericpulverulent material is forced from the position shown in FIG. 3 inproportion to the variable radial impact forces.

[0015]FIG. 5 shows a preferred embodiment of a self-contained batch ofcompensating material for introduction into a tire according to theinvention.

[0016]FIG. 6 shows another preferred embodiment of a self-containedbatch of compensating material for introduction into a tire according tothe invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0017] This invention will now be described in detail with reference topreferred embodiments thereof.

[0018] Reference is first made to FIGS. 1 and 2 of the drawings whichillustrate a conventional wheel assembly generally designated by thereference numeral 10 defined by a tire 111 and a metal rim 12 carrying atire valve or air valve 13 which includes a stem 14 having an internalthread. Under normal operating/road conditions, a valve core may bethreaded into the stem 14 of the tire valve 13. The valve stem 14 mayalso include a conventional external thread. The tire 11 is a radialtire. A biased tire essentially does not flex radially whereas a radialtire tends to flex radially, and in use the latter can be evidenced bysidewalls SW1, SW2 (FIGS. 1, 2, 3 and 5) which tend to bulge outwardlyunder load when resting or running upon a surface, such as a road R. Theamount of flex will vary depending upon such things as the total load ofthe vehicle, the speed of the vehicle, etc., and the load force can varyfrom wheel assembly to wheel assembly both in smaller passenger vehiclesand larger vehicles, such as tractor trailers. For example, a fullyloaded tractor trailer traveling at sixty miles an hour carrying heavysteel has a greater radial load force and therefore greater tire flexthan the same tractor trailer traveling unloaded, as occurs quite oftenin the hauling industry. Furthermore, as the load increases, the flex ofthe tire increases and the overall radius decreases. Obviously, if awheel assembly was conventionally “balanced” by utilizing lead weightsapplied to the rims, the lead weights would be effective to achievebalancing for a particular load and for a limited speed range, but notfor the full variations in load force and all speeds. Similarly, inpassenger vehicles with much lower gross vehicle weights, radial andlateral force variations may occur due to any irregularities in theuniformity or dimensions of the tire, any dimensional irregularities inthe wheel rim, and/or any dynamic imbalance or misalignment of thetire/wheel assembly. Such disturbances and vibrations will betransmitted to the sprung mass of the vehicle, producing an undesirableor rough vehicle ride, as well as reducing handling and stabilitycharacteristics of the vehicle.

[0019] Therefore, even when tire/wheel assemblies are balanced withtoday's sophisticated electronic balancing machines the wheels are notbalanced for all speeds and all radial force variations. It is thereforedesirable in both large tractor/trailer tire/wheel assemblies andsmaller passenger vehicle tire/wheel assemblies to provide for dynamiccompensation of radial and lateral force variations by introducing acompensation material into the tire.

[0020] The radial tire 11 includes a lower tire portion or a footprint Bdefined by a length L and a lateral breadth or width W whichcollectively define the instantaneous cross sectional area of the tirelower portion B in engagement with the supporting surface or road R whenthe wheel assembly 10 is stationary or is rotating. The tire T includesa conventional external tire tread T and beads Bl, B2 of the respectivesidewalls SW1, SW2 which engage the rim 12 in a conventional manner.

[0021] If the wheel assembly 10 and similar wheel assemblies associatedwith a vehicle (not shown) are not properly/perfectly balanced, theattendant unbalanced condition thereof during vehicle wheel rotationwill cause the tires to wear unevenly, wheel bearings will wearexcessively, shock absorbers operate at inordinately higher amplitudesand speeds, steering linkages/mechanisms vibrate excessively and becomeworn and overall vehicle ride is not only rough and dangerous, but alsocreates excessive component wear of the entire vehicle. These problemsare significant in automobiles, and are magnified in association withextremely large tires, such as truck tires, which are initially veryexpensive and if uncared for through unbalanced running, would adverselyaffect truck tire life, safety, and just as importantly, tireretreading.

[0022] Obviously, even if the wheel assembly 10 was balanced asperfectly as possible with lead weight, whether by static or dynamicbalancing, as road conditions change, as the tire 11 wears, as the loadof the vehicle changes, etc., the “perfect” balanced condition of thewheel assembly 10 is far less than perfect. Accordingly, not only mustthe wheel assembly 10 be balanced, but it is desired that the balancedcondition be retained during operation to stay in balance in response tovariations in road conditions, load forces, changes in speed, etc., asmight occur in conventional utilization as, for example, in the case ofa loaded versus an unloaded tractor trailer. Thus, as forces vary duringrotation of the wheel assembly 10 relative to the road R, the forcevariations are desirably compensated for dynamically using acompensating material within the tire which dynamically moves within thetire to facilitate maintaining load force equalization.

[0023] According to the present invention, effective tire balancingand/or a reduction in both radial and lateral forces acting on atire/wheel assembly can be achieved through the incorporation of acompensating material, preferably in the form of a dry lubricant incombination with a primary pulverulent material having a mesh size rangebetween 8 and 200. For purposes of this invention, the concept ofbalancing a vehicle and reducing external radial and lateral forcesacting on a tire shall be referred to as “total wheel balancing”.Although the invention will be described with reference to particularcompensating materials comprising dry particulates, compensatingmaterial within the scope of this invention includes liquids,particulate solids, and combinations thereof.

[0024] The primary or principal ingredient material in a solidcompensating material composition of the present invention may be eitheran inorganic material or an organic material in generally a particulateor more specifically a pulverulent form. Particulate materials are thoseformed by any process resulting in relatively small, discrete solids.Such processes include but are not limited to precipitation,polymerization, spraying, solidification, and comminution. Pulverulentmaterials are those particulate materials that have been reduced in sizethrough a suitable size reduction process, such as grinding, abrading,or other comminution processes. Suitable inorganic materials include,for example, powdered carbon, iron powder or filings, other metallicparticles such as lead shot, talc, and calcium carbonate (e.g.,limestone or calcite). Organic materials are for the most partpolymeric. The polymeric material is in a particulate or pulverulentform which may be either granules, a powder, or a dust.

[0025] Any compensating material that is stable and remains free flowingover all conditions of tire usage, and has a specific gravity greaterthan 1 may be suitable as a compensating material according to thepresent invention. In the preferred embodiment, a particulate materialcomprised of particles in sizes to be discussed below, can be used as awheel balancing material. An important requirement is that theparticulate material must be more thermally stable than the tire inwhich it is used under all tire operating conditions.

[0026] Organic polymeric materials for the practice of this inventionmay be either homopolymers (polymers of one monomer) or copolymers(polymers of two or more monomers). Probably, they are either thermosetor thermoplastic, although any material which is stable over the rangeof temperature extremes to which the tire is subjected is contemplated.

[0027] Thermoset resins useful in the practice of this invention includeurea-formaldehyde, melamine-formaldehyde, and phenolic resins. All ofthese are known molding compounds which are available in either granularor powdered form. Urea-formaldehyde and melamine-formaldehyde moldingpowders commonly contain a filler, particular alpha-cellulose.

[0028] Suitable thermoplastic polymers include polyvinyl chloride andvinyl chloride-vinylidene chloride copolymers (which normally contain amajor amount of vinyl chloride and a minor amount of vinylidenechloride), both of which may be plasticized; and nylon. Aramid fibersmay also be used in the practice of this invention. Both nylon andaramid are polyamides, although they have quite different chemicalcomposition and properties.

[0029] A particularly preferred pulverulent material is polymerizedurea-formaldehyde thermoset resin, available in granular, powder, ordust form. One such material is available under the trade name POLYPLUSmanufactured by U.S. Technology Corporation of Canton, Ohio. Thispulverulent material is non-volatile, nontoxic, noncorrosive andincludes the characteristics shown in the table below. TABLE Hardness(Barcol) 54 to 62 Hardness (Rockwell) M 110-120 Hardness (MOHS Scale)3.5 Specific Gravity (g/cc) 1.47-1.52 Bulk Density 58-60 IgnitionTemperature 530 C. Thermal Decomposition 450 C. Maximum OperatingTemperature 300 F. Izod Impact ASTM D256A-0.25-0.40 Water Absorption(ASTM D570-24 hr.) -0.4%-0.8% Water Absorption (MIL-A-85891A) -Max 10%Chemical Nature Inert

[0030] A preferred pulverulent material is composed of polymerized ureamolding compound (70% by weight), alpha cellulose filler (28% byweight), and pigments and additives (2% by weight). Although thepreferred compound is 70% urea, 28% alpha cellulose and 2% additives,100% urea formaldehyde or combinations of various materials (examples ofwhich have been disclosed above) are possible. Again, the inventioncontemplates a wide variety of suitable materials having the physicalcharacteristics as described above, and no limitation is intended inrelation to the preferred compensating materials set forth herein.

[0031] Particle sizes of a preferred particulate material used in thepractice of this invention may range broadly from about 8 to about 425mesh (U.S. Standard screen size). Additionally, the material maycomprise a polymodal distribution of particle sizes, including materialin different particle size ranges. Good results are obtainable with ablend or distribution of particle sizes within this range. Fineparticles move more quickly in response to small radial and lateralforces, while large particles move more slowly and in response togreater forces. Using particles within at least two distinct sizes orsize ranges, so that different size particles will move in reaction todiffering amount of forces. For example, it is believed that the smallerparticles will move first in response to smaller forces. The largerparticles then move in sort of a second stage of balancing or equalizingwhen forces are greater. One may use a particle blend having a bimodalparticle size distribution, e.g., a blend of relatively coarserparticles having particle sizes 20-40 mesh blended with relatively finerparticles which are predominantly from 50-100 mesh.

[0032] The particles must have a specific gravity greater than 1 so thatthey will move positively and as quickly as possible from one place toanother in response to external force. It has also been found that theaddition of dry powder lubricant or anti-agglomerating agents cansignificantly increase the effectiveness of the principal particulatematerial. The dry lubricant acts to coat the interior surface of thetire as well as the primary particulate material particles. In this wayparticle-particle friction of the particulate material is reduced as isfriction at the particulate particle-tire surface interface. The reducedfriction allows the particulate material to respond more quickly incounteracting radial and lateral forces acting on the vehicle wheelassembly.

[0033] When present in a sufficient amount the dry lubricant serves as avehicle within which the pulverulent material may freely flow or movelaterally and circumferentially within the tire. Further due to theextremely fine particle size of the lubricant, quantities of thelubricant itself may quickly move to positions within the tire in orderto counteract radial and lateral forces acting on the vehicle wheelassembly. Other anti-agglomerating agents to function in this manner arealso contemplated.

[0034] Presently, preferred dry lubricants or anti-agglomerating agentsare selected from a group of materials which include talc (or talcum),graphite, molybdenum disulfide, polytetrafluoroethylene, as well asvarious polymers, metals, metal oxides and salts which are known for useas solid lubricants. As with the primary pulverulent material, thelubricant is to be thermally and chemically stable at all operatingconditions of the tire and must be chemically and physically compatiblewith the primary pulverulent material. Currently of these materials, themost preferred lubricant is talc.

[0035] In another embodiment, a wheel balancing material may be in theform of a liquid or a liquid/solid combination, as described in U.S.Pat. No. 3,463,551, the teachings of which are fully incorporated byreference.

[0036] Referring to FIGS. 5 and 6, compensating materials according tothe invention as above described are formed into self-contained batchescomprising larger masses or agglomerates, as for example, pellets,briquettes, extrudates, or self-contained packages of free-flowingparticulates or liquids for charging into a pneumatic tire. These largermasses or agglomerates comprise a plurality of particles, usually alarge number of particles, which in the embodiment of FIG. 5 are eithercoherently or adherently held together tightly enough for shipping,handling and charging into a tire without premature disintegration. InFIG. 5, a briquette 30 comprises a predetermined amount of compensatingmaterial packaged in a convenient form for handling and introductioninto a tire prior to assembly with a wheel by simply placing thebriquette 30 into the tire interior. Upon subsequent mounting of thetire onto a wheel and the mounting of the tire/wheel assembly on avehicle, rotation of the assembly will cause the briquette 30 to breakdown into the individual particles from which it is made. The formationof the briquette 30 may be performed by typical processes to temporarilybind the individual particles together into a form which is easilyhandled and allows a predetermined amount of compensating material to beeasily chosen and added to the tire. The binding of the particlestogether in the briquette 30 allows the particles to stay together forshipping and handling, but once introduced into the tire, theagglomerate will disintegrate, releasing individual particles, whichthen perform their compensating and vibration damping function in themanner described. Thus a batch of compensating material isself-contained in the embodiment of FIG. 5, with the agglomerate ofmaterial retaining its agglomerated form during shipping, handling, andcharging without substantial loss of particulate material, i.e., thebatch remains substantially self-contained until after a tire containingthe batch is mounted on a wheel and the wheel is rotated at high speed,such as during operation of the vehicle.

[0037] In order to introduce wheel balancing material in the form ofagglomerates into a tire in an amount sufficient to balance a wheelassembly, it is necessary to introduce at least one self-containedbatch, and it may be necessary to introduce more than one self-containedbatch, as in the form of pellets, or a single self-contained batch, asin the form of a briquette 30. A self-contained batch is preferablysized such that it may be introduced into a tire as one batch (such as abriquette) or in a plurality of batches (such as pellets). The number ofself-contained batches required to provide the desired compensation ofradial and lateral force variations at the tire/road footprint will inturn be dependent on the characteristics of the tire/wheel assembly 10as well as the characteristics of the vehicle on which the assembly isto be used. For example, the amount of compensating material required toprovide the desired compensation function will increase as the size ofthe tire increases and as the gross vehicle weight increases. Further,it may be determined that a tire is imbalanced to a certain extent whichwould require a greater amount of compensating material. Othercharacteristics of a tire/wheel assembly, such as non-uniformity mayalso vary the amount of compensating material required. Thus, accordingto the invention, the self-contained batches of material may be formedin a variety of predetermined sizes to allow the desired amount ofmaterial to be easily chosen and introduced into the tire of aparticular tire/wheel/vehicle combination simply and effectively. Ingeneral, the preferred amount of the preferred compensating material forpassenger and light truck vehicles is in a range of 0.20-2.0 ounceswhile larger vehicles may use a larger amount, such as between 1.5-24ounces. These amounts may vary depending on particular characteristicsof the tire/wheel/vehicle. More particularly, the following ranges ofthe preferred compensating material are generally found to be effectivefor the following tire sizes. For a 13″ tire/wheel, an amount ofcompensating material for incorporation therein may range from about0.2-0.6 ounces. A 14″ tire/wheel may require an amount of compensatingmaterial in the range from about 0.4-0.9 ounces, while a 15″ tire/wheelmay require between 0.8-1.4 ounces. For a 16″ tire/wheel, the amount ofcompensating material that may be required may range from about 1.0-1.7ounces, while a 17″ tire/wheel may require an amount in the range fromabout 1.2-2.0 ounces. For truck tires, the amount of compensatingmaterial that would be desired for compensating radial and lateral forcevariations may lie in the range between 2.0-6.0 ounces. Again, dependingon the material itself as well as the characteristics of thetire/wheel/vehicle, the amount of material desired may vary. In general,the amount of material is sufficient to balance a wheel assembly andcompensate for radial and lateral force variations at the footprint.Thus, as tires of any size, ranging from passenger car tires to trucktires, can be treated with a composition according to this invention forthe purpose of balancing a wheel assembly and/or equalizing load forces.The amount (or weight) of powdered material per tire to be used willvary over a wide range, depending on the size of the tire and the amountthat the tire is out of balance, whether this amount be expressed as asuitable range or as an optimum amount. A suitable amount of material tobe used can be determined empirically, and indeed may requiredetermination empirically, since the amount that a tire is out ofbalance is determined empirically.

[0038] Based on the above, the self-contained batch of compensatingmaterial within the scope of this invention will allow the desiredamount of material to be added by positioning one or more of theself-contained batches on the interior of the tire. The briquette 30 maythus be formed in a single size, with one or more then used to achievethe desired amount, or could be produced in a predetermined amount foreach tire size as an example. Minor adjustments of the amounts usedcould also be supplemented by small pellets or the jike to fine tune theamount for a particular tire/wheel assembly.

[0039] In the embodiment of FIG. 5, the composition of an agglomerate(e.g., a pellet, briquette, or extrudate) may be either (1) a binderlessagglomerate in which particles are self-adhesively held together, (2) anagglomerate comprising particles, such as pulverulent material, and abinder, or (3) a coated product.

[0040] A binderless pellet or briquette consisting essentially of 100%pulverulent or other particulate material self-adhesively held togetheras above described, is a composition according to this first embodiment.The pulverulent or other particulate material must be sufficiently selfadhesive to form binderless agglomerates such as pellets or briquettes.

[0041] Pellets can be prepared by compressing an initially particulatematerial, which is typically light and bulky, into pellets of desiredsize and shape (e.g., spherical) on a pellet mill. Briquettes can beformed by shaping a particulate material with heat and pressure in abriquetting mold. Other pre-formed shapes can be produced usingcontinuous forming processes such as extrusion followed by chopping.Binderless pellets, briquettes, and extrudates require a startingparticulate material which is sufficiently cohesive so that theresulting pellet, or briquette, or extrudate will retain the structuralintegrity until charged into a tire according to this invention. Also,the processing conditions (e.g., degree of compression) must be suchthat the pellet, briquette, or extrudate remain substantiallyself-contained during shipping, handling, and charging into a tire, butwill break apart in a tire upon rotation of the tire, releasingindividual particles which will then perform their desired function.Depending on the compensating material, these processing conditionswould be readily determined by one of ordinary skill in the art withoutundue experimentation.

[0042] A second type of composition comprises particles of pulverulentmaterial and a binder. The binder holds particles of pulverulentmaterial so that a coherent mass such as a pellet, briquette, orextrudate can be formed. Binders may be either inorganic or organic. Forinstance, certain resinous materials are capable of performing thisfunction. Certain inorganic materials, as for example sodium silicate(“water glass”) can also be used. Typically, the binder will be soft athigh temperature and hard at room temperature. The binder ordinarilyconstitutes from about 1 to about 20% of total composition weight, moretypically from about 2% to about 10% by weight.

[0043] A third form of composition according to this invention is acoated product. The coating material may be either abradable orthermally activated. An abradable coating is one which would undergorupture or disintegration due to mechanical forces placed on it in arotating tire. An abradable material may be either a thin polymer or aninorganic coating material. Inorganic coating materials include liquidsodium silicate. A thermally activated coating material is one having alow melting temperature, lower than that attained in a tire due to heatbuild up in normal operation of a vehicle. A number of low meltingtemperature materials are suitable. The coating material may coat eitherindividual particles or may form an outer layer of a pellet orbriquette, the particles of pulverulent material forming the interior.In either case the amount of coating agent will be from about 1% toabout 20% by weight, based on total composition weight, and morepreferably, from about 2% to about 10% of total composition weight.

[0044] The compositions above described may be formed by knownprocedures. Pellets, briquettes and other agglomerates or extrudatesaccording to this invention may be made of any convenient size andshape. Pellets are typically either spherical or ellipsoidal. Briquettesare typically pillow shaped as shown in FIG. 5. Extrudates are typicallycylindrical. None of these shapes is critical. Size also is notcritical, except that an agglomerate should be no larger than isnecessary to contain wheel balancing material sufficient to charge agiven tire size using one self-contained batch. An agglomerate can besmall enough to permit charging of a plurality of self-containedbatches.

[0045] In another embodiment as shown in FIG. 6, a self-contained batchof particulate wheel balancing material is made in the form of a bag 40containing free flowing compensating material. A bag is also suitable asa self-containment form for liquid and liquid/solid materials. A bag ispreferably made of a material that will abrade, tear or shred uponrotation of an assembled wheel. Suitable materials include generallypaper and plastic. In FIG. 6, the bag 40 is designed to contain apredetermined amount of compensating material to allow shipping,handling and charging of a tire/wheel assembly without substantial lossof material, and then to break down to release the free-flowingparticles or other material, In an embodiment of bag 40, a papermaterial may be used to form bag 40 in a conventional manner using form,fill and seal equipment. In such equipment, bag 40 is produced with aninitially open top, the compensating material is placed therein, and thetop is then sealed. In a particular example, a 20 lb. paper was used toform bag 40, with the edges thereof hot sealed using a 5 lb. low densitypolyethylene glue. Other paper weights or glues may also be suitable fora given tire/wheel assembly. Thus a bag of compensating material isself-contained in that it will retain substantially all of the materialbatch in the bag until the bag is transferred into a tire.

[0046] Also in this embodiment, the bag 40 may be produced of apolymeric film, similar to typical poly bags. In such an embodiment, theedges of the bag can be easily heat sealed, eliminating any requirementfor gluing. The bag 40 can also be double-sealed to facilitate handlingand also subsequent degradation of the bag to release the compensatingmaterial. In such an embodiment, a primary seal 42 can be formed at thetop edge of bag 40. The seal 42 would preferably be a relatively strongseal to withstand shipping and handling. A secondary seal 44 may also beprovided in the bag 40, which preferably would be a weaker seal, beingmore easily opened to release material from within the bag 40. In use,the primary seal could be torn away or otherwise removed for charging ofa tire, leaving only the secondary seal 46 which will easily releasematerial upon subsequent rotation of the assembly. To facilitate this, aperforation line 46 could be formed between seals 42 and 44. Othersuitable sealing techniques to facilitate this process are alsocontemplated.

[0047] In a further embodiment of a self-contained batch using acontainer such as a bag 40 for the free-flowing material, may also useperforations 48 in the bag material (whether paper or polymeric) ifdesired, to facilitate shredding of the bag 40 and release of thecompensating material. Such perforations can be formed usingconventional perforating equipment. It should be understood that anysuch perforations would have to be of a character to not allow theescape of material from within the bag 40 until bag 40 has been chargedinto a tire. The perforations, or microperforations, if any, aresufficiently small to prevent loss of wheel balancing material throughthe perforation holes, but also facilitate shredding of the bag 40 uponrotation of the tire.

[0048] Use of a bag is preferential for materials that are not easilyagglomerated, such as metal shot and other metallic materials. Use of abag as a containing means is not therefor limited and can be used forany compensating material including particulate or pulverulent material,liquid materials or combinations within the scope of this invention.

[0049] Self-contained batches such as agglomerates and bags of materialaccording to this invention may be charged or introduced into a tire inany desired fashion. If the self-contained batches were formed in theproper size such as small pellets, it may be possible to introduce suchpellets into a tire through its valve. It will usually be moreconvenient, however, to use larger size agglomerates (pellets,briquettes, or extrudates) or bags and to introduce them into a tirebefore the tire is mounted on a rim to form a wheel assembly. Theself-contained batch of material can be introduced into the tire priorto assembly with a wheel, either at original manufacture or duringreplacement or repair. Introduction or transfer of self-containedbatches into a tire can be by manual transfer or by automatic, machinetransfer.

[0050] While this invention has been described with reference topreferred embodiments thereof, it shall be understood that suchdescription is by way of illustration and not by way of limitation.

what is claimed is:
 1. A method for introducing a compensating materialinto a tire/wheel assembly comprising the steps of: providing a tire;providing at least one self-contained batch of compensating material;transferring said at least one self-contained batch of compensatingmaterial into an interior of said tire; and mounting said tire on awheel to form a tire/wheel assembly; wherein compensating material isreleased from said at least one self-contained batch such that saidcompensating material is able to freely flow within said tire/wheelassembly.
 2. The method of claim 1 , wherein said compensating materialis a particulate material.
 3. The method of claim 2 , wherein saidparticulate material comprises a polymer.
 4. The method of claim 2 ,wherein said particulate material comprises urea formaldehyde resin andcellulose filler.
 5. The method of claim 2 , wherein said particulatematerial comprises a metallic material.
 6. The method of claim 2 ,wherein said particulate material comprises an inorganic material. 7.The method of claim 1 , wherein said compensating material comprises atleast in part a liquid material.
 8. The method of claim 1 , wherein saidself-contained batch is provided in at least one device to contain saidmaterial, wherein said device is destroyed to release said material. 9.The method of claim 8 , wherein said at least one device to contain saidmaterial is at least one bag.
 10. The method of claim 9 , wherein saidat least one bag is a paper or plastic bag.
 11. The method of claim 8 ,wherein said at least one device is adapted to release said compensatingmaterial after positioning thereof inside said tire and upon rotation ofsaid tire/wheel assembly.
 12. The method of claim 8 , wherein saiddevice is made of a material which will break down upon being rotatedwithin said tire/wheel assembly to release said compensating material.13. The method of claim 9 , wherein said bag has a plurality ofperforations therein.
 14. The method of claim 9 , wherein said bag has aprimary seal and a secondary seal, wherein said primary seal is arelatively stronger seal than said secondary seal.
 15. The method ofclaim 14 , wherein said primary seal is removed prior to introduction ofsaid bag into a tire.
 16. The method of claim 1 , wherein saidself-contained batch comprises an agglomerate.
 17. The method of claim16 , wherein said agglomerate is selected from the group consisting ofpellets, briquettes, and extrudates.
 18. The method of claim 16 ,wherein said agglomerate is comprised of particles which areself-adhesively held together.
 19. The method of claim 16 , wherein saidagglomerate is comprised of particles held together with a binder. 20.The method of claim 16 , wherein said agglomerate is comprised ofparticles held together using an exterior coating surrounding saidparticles.
 21. The method of claim 1 , wherein said transferring step isselected from the group consisting of manual transfer and machinetransfer.
 22. A method of compensating for radial and lateral forcevariations at the tire/road footprint of a tire/wheel assemblycomprising the steps of: providing a predetermined amount ofcompensating material in at least one self-contained batch in a formpreventing said compensating material from freely flowing apart fromself-contained batch, putting said self-contained batch into an interiorof said tire, mounting said tire on a wheel to form a tire/wheelassembly, mounting said tire/wheel assembly on a vehicle, wherein saidcompensating material is released from said self-contained batch anddisperses within said tire/wheel assembly to provide compensation ofsaid force variations.
 23. A method for introducing a compensatingmaterial into a tire/wheel assembly comprising the steps of: providing atire; providing at least one self-contained batch of compensatingmaterial, said at least one self-contained batch comprising at least onebag containing a predetermined amount of said compensating material,placing said at least one bag into an interior of said tire; mountingsaid tire on a wheel forming a tire/wheel assembly; and mounting saidtire/wheel onto a vehicle; inflating said tire/wheel assembly wherebysaid at least one bag becomes ruptured to release said compensatingmaterial within said tire/wheel assembly; wherein said predeterminedamount of said compensating material is directly related the size ofsaid tire.